Recent years have seen increasingly advances in upsizing of a telescope system which receives observation light and electric waves from space so as to make celestial observations, in order to carry out highly precise observation with a higher resolution. Especially, the dominating telescope system has a reflecting mirror which consists of a single mirror when its opening diameter is of the order of several meters. However, when the reflecting mirror has an opening diameter of the order of several tens of meters or more, since there arises a manufacturing problem if the reflecting mirror consists of a single mirror, a technology for assembling one reflecting mirror by combining a plurality of mirrors (referred to segmented mirrors from here on) into which a single mirror is divided has been developed. For example, JP, 2003-188641,A which is a Japanese patent application discloses a related art reflecting mirror apparatus. This reflecting mirror apparatus disclosed by JP, 2003-188641,A has a single reflecting mirror in which a plurality of segmented mirrors are arranged. These segmented mirrors are supported, via an actuator, by a back structure which is a supporting structure.
A problem with the reflecting mirror apparatus using such a related art supporting method is that since the direction of the optical axis is changed so as to fall within a driving range, a self weight deformation of the back structure resulting from a change in the attitude of the whole of the reflecting mirror apparatus, a deformation of the back structure due to the pressure of winds blowing against the reflecting mirror, and a deformation of the back structure which is caused by a temperature distribution which occurs therein degrades the mirror surface accuracy of the reflecting mirror consisting of the plurality of segmented mirrors. A further problem is that since deformations which thus appear in the back structure may include not only a mode deformation which appears in the whole structure, but also a deformation which appears nonuniformly and locally in the back structure, the deformations are not canceled perfectly by using such a technique as shape maintenance control through estimation of the mode deformation, and therefore there cause displacements of the local positions of the plurality of segmented mirrors and the mirror surface accuracy of the reflecting mirror degrades.    Patent reference 1: JP, 2003-188641,A